1. Field of the Invention
This invention relates to a thin film magnetic head usable for a magnetically recording and reproducing device such as a magnetic disk drive device and a method for forming a protective layer on an opposing surface to a recording medium of a slider constituting the magnetic head.
2. Related Art Statement
A thin film magnetic head uses as a bearing an airflow generated from a high speed rotation of a magnetic recording disk (magnetic disk). The airflow floats the magnetic head from the magnetic disk by a minute floating height, and avoids the abrasion of the magnetic head. When the magnetic disk corrodes or an electromagnetic conversion element, loaded on a slider constituting the magnetic head, corrodes, metallic protrusions due to the corrosions are produced on the magnetic disk or the conversion element, often resulting in the fluctuation of the floating height of the slider, the abrasion of the magnetic disk or the conversion element and the destruction of the magnetically recording data in the magnetic disk because of the contact between the magnetic disk and the conversion element. For avoiding the above problems, in the past, DLC (diamond-like carbon) protective films were provided on the opposing surfaces of the slider and the magnetic disk. The DLC has the characteristics of the corrosion prevention and the enhancement of the wear resistance against the contact between the magnetic disk and the conversion element at a rotation start and a rotation stop and the contact between the minute foreign particles and the magnetic disk or the conversion element.
The DLC films has a fluorine carbon layer on its outermost surface in numerous case (Japanese Patent Application Laid-open publication Kokai Hei 10-68083:JP A 10-68083). The DLC film having such a structure lowers the surface energy and the absorption coefficient of the outermost surface thereof, which can prevent the sticking between the outermost surface and the magnetic disk or the absorption of contaminants on the outermost surface.
Since the DLC film has a resistivity of 1010-1012 xcexa9cm, it also maintains the electrical insulation between the slider of the thin film magnetic head and the magnetic disk when the slider and the magnetic disk contact each other.
In the magnetic disk drive device, all the aspects angles are considered for increasing a recording density. One of them is to reduce a spacing loss by decreasing the distance between the electromagnetic conversion element loaded on the slider and the magnetic disk. The reduction of the spacing loss is normally carried out through the decreasing of the floating height of the slider of the thin film magnetic head for the magnetic disk and of the thickness of the protective film. Since the decreasing of the floating height is restricted because of the contamination on the surface of the magnetic head, generally, the decreasing of the thickness of the protective film may be carried out effectively.
The DLC film, however, has a poor adhesion for the slider surface. It is known as a means for enhancing the adhesion of the DLC film to form an adhesive layer between the surface of the slider and the DLC protective layer. At present, the adhesive layer is composed of an xcex1-Si (amorphous silicon). The adhesive layer made of the xcex1-Si does not have a thickness of not more than 2 nm so that it can have uniform thickness. The thickness of the adhesive layer determines the total thickness of the protective layer. Moreover, if the protective layer to be formed on the adhesive layer is thinner, the electric insulation between the slider and the magnetic disk can not be maintained when they are contacted. Thus, on account of the above reason, the reducing of the thickness of the DLC protective layer is restricted and thereby, the reducing of the spacing loss and the enhancement of the recording density come to a deadlock.
It is an object of the present invention to provide a thin film magnetic head with a protective film having a small spacing loss and suitable for a high density recording and a method for forming the protective film.
It is another object of the present invention to provide a thin film magnetic head with a protective film without an adhesive layer having a mechanical strength equal to or more than that of a DLC and a method for forming the protective film.
It is still another object of the present invention to provide a thin film magnetic head in which dusts are unlikely to be absorbed and the slider constituting the magnetic head and a recording medium are unlikely to be stuck each other and a method for forming a protective film usable for the magnetic head.
It is further object of the present invention to provide a thin film magnetic head having a small surface-friction coefficient and a method for forming a protective film usable for the magnetic head.
To iron out the above problems, thin invention relates to a thin magnetic head comprising a slider having an opposing surface to a medium, at least one magnetic conversion element supported by the slider and a protective film comprising of a SiN film and a surface-lubricous layer.
An ideal protective has an adhesive layer for the surface of the slider, an intermediate layer having a large mechanical strength and a surface layer having a small absorption coefficient and a small friction coefficient. However, the above problems in using the DLC protective film arises from the adhesive layer between the protective layer and the slider surface. The problems are ironed out by using a protective film without an adhesive layer which has a mechanical strength equal to or more than that of the DLC protective film.
The inventors has found out that a SiN film is suitable for the protective film, which can iron out the above problems. The SiN film has a good adhesion for the material constituting the slider of the thin film magnetic head. Thus, the protective film does not have need of an adhesive layer, so that the thin film magnetic head can have the protective film without an adhesive layer with a mechanical strength more than that of the DLC protective film.
Since the SiN film has a larger hydrophile than that of the DLC film or a water-repellent DLC film, without any processing, the absorption of dust, the sticking between the slider and a recording medium and the increase of the surface-friction coefficient, etc. are likely to occur. These problems are ironed out by forming a lubricous layer on the surface of the SiN film (hereinafter, often called as a xe2x80x9csurface-lubricous layerxe2x80x9d). That is, the lubricous layer formed on the surface of the SiN film almost never absorb dusts and stick the slider to the recording medium, leading to the production of the thin film magnetic head having a small friction coefficient. The surface-lubricous layer is required to satisfy the conditions of having a small surface energy for preventing surface-absorption and the occurrence of a shearing at a friction boundary, not in the lubricous layer itself, etc. Although the surface-lubricous layer may be made of a liquid lubricous material such as polyfluoroether or a solid lubricous material such as graphite and hexagonal boron, it is preferably composed of a property modified layer in the outermost surface of the protective film itself. The property-modified layer may be composed of a SiO2 film or a fluorocarbon layer (CF film) formed in the top of the protective film. Of them, the CF film is more favorable because it can have a small surface-absorption coefficient and its extremely thin thickness.
The CF film has difficulty in being formed on the top of the SiN film by using a fluorine plasma as in forming the DLC film, because SiF is energetically stable. Accordingly, the CF film having a thickness of not more than 1 nm is directly formed on the SiN film.
The protective film may have an intermediate layer. The intermediate layer exists between the SiN layer and the surface-lubricous layer, composed of the constituting atoms of the SiN layer and the surface-lubricous layer and have a thickness of 0.3-0.5 nm.
In the forming method of the protective film according to the present invention, the SiN film is formed on the opposing surface to a recording medium of the thin film magnetic head by an ECR sputtering method.
Although it is known in the Japanese Patent Application Kokai Hei 63-91814:JP-A 63-91814) that the SiN film is employed for the protective film of the thin film magnetic head, the SiN film is formed by a CVD method or a sputtering method. The CVD- or sputtering-formed SiN film can not have a mechanical strength equal to or more than that of the DLC film.
On the contrary, the ECR sputtering-formed SiN film can have a mechanical strength equal to or more than that of the DLC film and have a thinner thickness than that of the DLC film.
In the present invention, a surface-lubricous layer containing a compound of carbon and fluorine is formed on the surface of the SiN film.
The other objects, configurations and advantages will be explained in detail, with reference to the attaching drawings in embodiments.